Instrument for measuring electromagnetic signals

Abstract

A device and method for measuring electromagnetic signals that can be used to take measurements at or near the sea floor. The device comprises a central housing, a data management system located within the housing and at least two arms extending outwards from the housing. Each arm comprises a flexible elongate sheath attached to the housing, a sensor head, a flexible electrical cable attached to the sheath and connecting the sensor head to the data management system and a rod which is removeably locatable within the sheath. The rod is connectable relative to the housing at one end and connectable relative to the sensor head at the end remote from the housing.

1. An electromagnetic signal detecting device, which comprises electromagnetic signal detecting instruments borne by arms, wherein each arm comprises a removable rod and a flexible conduit arranged to receive the rod, the device further comprising:
 a central housing; 
 a data management system located within the housing; 
 at least two arms, the arms extending outwards from the housing; 
 wherein each arm comprises— 
 a sensor head, the sensor head constituting at least part of the electromagnetic signal detecting instruments; 
 a flexible elongate sheath attached to the housing, the flexible elongate sheath constituting at least part of the flexible conduit; 
 a flexible electrical cable attached to the sheath and connecting the sensor head to the data management system; and 
 the rod which is removably locatable within the sheath; 
 wherein the rod is more rigid than the sheath and one end of the rod is connectable relative to the housing and one end of the rod remote from the housing is connectable relative to the sensor head, and wherein each rod is connected to a second similar rod at a point along said each rod which is remote from the housing, one end of the second rod being independently connectable relative to the housing. 
 
     
     
       2. An electromagnetic signal detecting device according to  claim 1 , suitable for use under water. 
     
     
       3. An electromagnetic signal detecting device according to  claim 1 , wherein the rod is straight and extends away from the point of attachment relative to the housing, substantially perpendicularly to the housing. 
     
     
       4. An electromagnetic signal detecting device according to  claim 1 , wherein the rod is connected to a bracket located on the housing. 
     
     
       5. An electromagnetic signal detecting device according to  claim 1 , wherein the rod is fabricated from fiber glass. 
     
     
       6. An electromagnetic signal detecting device according to  claim 1 , wherein the number of arms is four, comprising two pairs of arms which are substantially parallel to each other, one pair of arms being substantially orthogonal to the other. 
     
     
       7. An electromagnetic signal detecting device according to  claim 1 , wherein the sensor head is attached to the sheath at the end of the sheath remote from the housing. 
     
     
       8. An electromagnetic signal detecting device according to  claim 1 , wherein each sensor head comprises one or more electrical sensors. 
     
     
       9. An electromagnetic signal detecting device according to  claim 1 , wherein each sensor head comprises two electrical sensors. 
     
     
       10. An electromagnetic signal detecting device according to  claim 1 , wherein one or more magnetic sensors are located in the central housing. 
     
     
       11. An electromagnetic signal detecting device according to  claim 1 , wherein the flexible electrical cable is attached to the sheath with one or more connectors. 
     
     
       12. An electromagnetic signal detecting device according to  claim 11 , wherein the flexible electrical cable is incorporated in the fabric of the sheath. 
     
     
       13. A method of deploying an electromagnetic signal detecting device having a housing which comprises;
 storing the device, the device comprising electromagnetic signal detecting instruments borne by arms, a data management system located within the housing and at least two arms extending outwardly from the housing, wherein each arm comprises:
 a sensor head constituting at least part of the electromagnetic signal detecting instruments; 
 a flexible elongate sheath attached to the housing; 
 a flexible electric cable attached to the sheath and connecting the sensor head to the data management system; and 
 a rod removably locatable within the sheath, wherein the rod is more rigid than the sheath; 
 
 locating the rods within the flexible elongate sheaths, connecting the rods relative to the housing at one end and connecting the rods relative to the sensor head at an end of each rod remote from the housing, wherein each rod is connected to a second similar rod at a point along said each rod which is remote from the housing, one end of the second rod being independently connectable relative to the housing; and 
 using the device to detect electromagnetic signals. 
 
     
     
       14. A method according to  claim 13 , additionally comprising the step of positioning the device on or near the seafloor before using the device to detect electromagnetic signals. 
     
     
       15. A method of deploying an electromagnetic signal detecting device according to  claim 13 , wherein a controlled electromagnetic source near the sea floor is the origin of the electromagnetic signals.